Fixation assembly

ABSTRACT

A fixation assembly having a driver, a holding sleeve, and an alignment mechanism is disclosed. The driver may include a driver body and a coupling extending from a distal end of the driver body. The holding sleeve may have a holding sleeve body, a channel extending through the holding sleeve body, and a fixation element coupler disposed at a distal portion of the holding sleeve body. The channel may be configured to receive the driver, and the fixation element coupler may be configured to temporarily hold a fixation element. The alignment mechanism may extend from the holding sleeve, and may have at least one alignment member configured to engage an underlying structure to which the fixation element is to be affixed so as to align the fixation element and driver assembly with respect to the underlying structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/087,659, filed Apr. 15, 2011, pending. The aforementioned patentapplication is incorporated herein by reference.

BACKGROUND OF THE INVENTION

During many medical procedures, fixation elements such as screws may beused to affix certain devices, such as implants, to an underlyingstructure such as bone or even another implant. In certain vertebralfixation procedures, once fixation members have securely attached animplant to the underlying structure, a blocking plate is affixed to theimplant using a screw to thereby prevent the fixation members frombacking out of the implant. For example, the blocking plate can beattached to an intervertebral implant after the implant has been affixedto a superior vertebral body and an inferior vertebral body using one ormore fixation members. Such screws are typically affixed using driversthat securely hold the screw so as to prevent the screw frominadvertently falling into the patient prior to the placement of thescrew.

Devices for retaining screws on a screw driver are known, but many ofthe prior devices depend on a linear side-bearing force from a clamp orother mechanism to hold the screw in place. Other methods of temporarilyretaining a screw to a driver include using a central threaded rod downthe center of the driver or a driver with a spring-wire off axis of thedriver that may protrude laterally into the screw.

SUMMARY OF THE INVENTION

A fixation assembly configured to temporarily hold, align and affix afixation element to an underlying structure such as an implant isdisclosed. The fixation assembly may include a driver, a holding sleeve,and an alignment mechanism. The driver may include a longitudinallyelongate driver body, and a coupling that extends distally from a distalend of the driver body. The coupling may be configured to engage acoupling defined by a head of the fixation element.

The holding sleeve may include a holding sleeve body and a channel thatextends longitudinally through the holding sleeve body. A distal end ofthe holding sleeve body defines a fixation element coupler that isconfigured to temporarily attach the fixation element to the holdingsleeve. In one embodiment, the fixation element coupler includesinternal threads defined by the channel of the holding sleeve. Thethreads of the holding sleeve may be configured to engage externalthreads defined by the head of the fixation element. The driver isconfigured to extend through the channel of the holding sleeve andcouple to the holding sleeve to thereby define a driver and holdingsleeve assembly. The driver may be coupled to the holding sleeve suchthat the driver may translate a predetermined distance with respect tothe holding sleeve.

The alignment mechanism may include an alignment mechanism body and achannel that extends through the alignment mechanism body. The channelis configured to receive the driver and holding sleeve assembly. Thealignment mechanism further includes a pair of alignment members thatextend distally past a distal end of the holding sleeve. The alignmentmembers may be configured to engage apertures defined by a fixationplate of an intervertebral implant.

The fixation assembly may be configured to affix a fixation elementhaving a shaft and a head disposed at a proximal end of the shaft. Theshaft may include threads that are configured to engage threads definedby the fixation plate of the intervertebral implant. Similarly, the headmay include threads that are configured to engage threads defined by thefixation element coupler of the holding sleeve. The pitch of the threadson the head and on the shaft may be similar such that the rate at whichthe fixation element is advanced into the fixation plate, is similar tothe rate that the fixation element disengages from the holding sleeve.

In another embodiment, the fixation assembly may include a driver, afixation element coupler, and an alignment mechanism. The driver mayhave a driver body and a coupling extending from a distal end of thedriver body. The coupling may be configured to engage a coupling definedby a fixation element. The fixation element coupler may be configured totemporarily hold the fixation element. At least one of the driver andthe fixation element coupler may be translatable relative to the other.The alignment mechanism may have at least one alignment memberconfigured to engage an underlying structure to which the fixationelement is to be affixed so as to align the fixation element, thedriver, and the fixation element coupler with respect to the underlyingstructure.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofa preferred embodiment of the application, will be better understoodwhen read in conjunction with the appended drawings. For the purposes ofillustrating the fixation assemblies of the present application, thereis shown in the drawings preferred embodiments. It should be understood,however, that the application is not limited to the precise arrangementsand instrumentalities shown. In the drawings:

FIG. 1A is a perspective view of a fixation assembly constructed inaccordance with one embodiment, the fixation assembly engaging anintervertebral implant that is disposed in an intervertebral space;

FIG. 1B is a perspective view of the fixation assembly shown in FIG. 1A,the fixation assembly including at least one fixation element, ablocking plate, and a driver assembly that is configured to securelyhold, align, and drive the fixation element, the driver assemblyincluding a driver, a holding sleeve disposed about the driver, and analignment mechanism that is configured to engage a structure, such asthe intervertebral implant shown in FIG. 1A, to which the fixationelement is to be affixed;

FIG. 1C is a top plan view of the driver assembly shown in FIG. 1B;

FIG. 1D is a sectional side elevation view of the driver assembly shownin FIG. 1C taken through the line 1D-1D;

FIG. 2 is a perspective view of the driver shown in FIG. 1A;

FIG. 3A is a perspective view of the holding sleeve shown in FIG. 1A;

FIG. 3B is a perspective view of the holding sleeve in accordance withanother embodiment;

FIG. 4 is a perspective view of the alignment mechanism shown in FIG.1A;

FIG. 5A is a perspective view of the fixation element shown in FIG. 1A,the fixation element having a threaded head and a threaded shaft;

FIG. 5B is a top plan view of the fixation element shown in FIG. 5A;

FIG. 5C is a bottom plan view of the fixation element shown in FIG. 5A;

FIG. 5D is a side elevation view of the fixation element shown in FIG.5A;

FIG. 6A is a perspective view of the blocking plate shown in FIG. 1A;

FIG. 6B is a top plan view of the blocking plate shown in FIG. 6A;

FIG. 6C is a bottom plan view of the blocking plate shown in FIG. 6A;

FIG. 6D is a front elevation view of the blocking plate shown in FIG.6A;

FIG. 6E is a side elevation view of the blocking plate shown in FIG. 6A;

FIG. 7 is a perspective view of an intervertebral implant having afixation plate to which the fixation element of FIGS. 5A-5D and theblocking plate of FIGS. 6A-6E are to be affixed;

FIG. 8A is a top plan view of a portion of the fixation assemblyillustrated in FIG. 1A, showing the driver engaging the head of thefixation element;

FIG. 8B is a top plan view of a portion of the fixation assemblyillustrated in FIG. 8A, showing the driver retracted within the holdingsleeve, and the head of the fixation element temporarily coupled to theholding sleeve;

FIG. 8C is a top plan view of a portion of the fixation assemblyillustrated in FIG. 8B, showing the alignment mechanism translateddistally;

FIG. 8D is a top plan view of a portion of the fixation assemblyillustrated in FIG. 8C, showing the alignment mechanism engaging thefixation plate of the intervertebral implant of FIG. 7;

FIG. 8E is a sectional top plan view of the portion of the fixationassembly illustrated in FIG. 8D, showing the alignment mechanismengaging the fixation plate of the intervertebral implant;

FIG. 8F is a top plan view of a portion of the fixation assemblyillustrated in FIG. 8D, showing the driver affixing the fixation elementand the blocking plate to the fixation plate of the intervertebralimplant;

FIG. 8G is a top plan view of a portion of the fixation assemblyillustrated in FIG. 8F, showing the fixation element and the blockingplate fully affixed to the intervertebral implant;

FIG. 9A is a perspective view of a fixation assembly constructed inaccordance with another embodiment, the fixation assembly including adriver assembly that is configured to securely hold, align, and drive afixation element, the driver assembly including a driver, and a holdingsleeve disposed about the driver, the holding sleeve including anintegrated alignment mechanism that is configured to engage a structureto which the fixation element is to be affixed;

FIG. 9B is a perspective view of the driver shown in FIG. 9A;

FIG. 9C is a perspective view of the holding sleeve shown in FIG. 9A;

FIG. 9D is a sectional perspective view of the driver assembly shown inFIG. 9A taken through the line 9D-9D;

FIG. 9E is a top plan view of the fixation assembly shown in FIG. 9Aaffixing a fixation element to an intervertebral implant;

FIG. 10A is a perspective view of a driver assembly constructed inaccordance with another embodiment, the driver assembly including adriver, a holding rod extending through a channel of the driver, and analignment mechanism disposed about the driver;

FIG. 10B is an exploded assembly view of the driver assembly shown inFIG. 1 OA;

FIG. 11A is a perspective view of a driver assembly in accordance withanother embodiment, the driver assembly including a driver, a two parttube capable of rotating about the driver, and an alignment mechanism;and

FIG. 11B is an exploded assembly view of the driver assembly shown inFIG. 11A.

DETAILED DESCRIPTION OF THE INVENTION

Certain terminology is used in the following description for convenienceonly and is not limiting. The words “right”, “left”, “lower” and “upper”designate directions in the drawings to which reference is made. Thewords “inwardly” or “distally” and “outwardly” or “proximally” refer todirections toward and away from, respectively, the geometric center ofthe bone anchor and related parts thereof. The words, “anterior”,“posterior”, “superior,” “inferior” and related words and/or phrasesdesignate preferred positions and orientations in the human body towhich reference is made and are not meant to be limiting. Theterminology includes the above-listed words, derivatives thereof andwords of similar import.

As shown in FIGS. 1A-1D, a fixation assembly 8 includes a fixationelement 14 and a driver assembly 10 that is configured to securely hold,align, and drive the fixation element 14 into an underlying structure,which can be any desired bone such as a vertebral body, an implant, softtissue, or any alternative underlying structure configured to receivethe fixation element 14. As shown in FIG. 1A, the driver assembly 10 maybe configured affix the fixation element 14 to an intervertebral implant204 that is anchored within an intervertebral space “S” that is definedbetween adjacent vertebral bodies V_(S) and V_(I).

The driver assembly 10 is elongate in a longitudinal direction L anddefines a proximal end P and a distal end D that is opposite theproximal end P along the longitudinal direction L and is configured toretain the fixation element 14 so as to define a driving end of thedriver assembly 10. The driver assembly 10 is configured to securelyhold the fixation element 14 and then subsequently align and seat thefixation element 14 in the underlying structure. It should beappreciated that the fixation element 14 can be permanently driven intothe underlying structure, such that the fixation element 14 remainsimplanted after the surgical procedure has been completed. For instance,the fixation element 14 can be temporarily coupled to the driverassembly 10 prior to seating the fixation element 14 into its permanentplacement. By temporarily coupling the fixation element 14 to the driverassembly 10 during placement, the fixation element 14 will notinadvertently disengage from the driver assembly 10 and fall into apatient.

The driver assembly 10 may be operable to align and seat a variety offixation elements 14 that are utilized in a variety of applications. Forinstance, the fixation assembly 8 can further include a blocking plate16, and the driver assembly 10 may be configured to seat or otherwisedrive a screw into a fixation plate of the intervertebral implant 204shown in FIG. 1A to thereby affix the blocking plate 16 to the fixationplate. The blocking plate 16 can prevent fixation members, such asfixation members 216 that attach the implant 204 to the vertebra V_(S)and V_(I) from backing out after being implanted in the underlyingstructure.

As shown in FIGS. 1B-1D, the driver assembly 10 includes a driver 18 anda holding sleeve 22 that is disposed about the driver 18. The holdingsleeve 22 is configured to hold or otherwise support the fixationelement 14 while the driver 18 is configured to drive the fixationelement 14. For instance, the driver 18 is configured to drive thefixation element 14 so as to cause the fixation element 14 to disengagefrom the holding sleeve 22 while simultaneously engaging the underlyingstructure to which it is to be affixed. As shown in FIG. 1B, the driverassembly 10 can further include an alignment mechanism 26 that isconfigured to engage the underlying structure to which the fixationelement 14 is to be affixed, so as to align the fixation element 14 asit is being driven by the driver 18. In the illustrated embodiment, thealignment mechanism 26 defines an alignment sleeve 30 that at leastpartially surrounds or encircles a distal portion of the holding sleeve22. Though it should be understood that the alignment mechanism 26 andthe holding sleeve 22 may be one solid piece (e.g. as shown in FIG. 9D).The driver 18, the holding sleeve 22, and the alignment mechanism 26 maybe made from any biocompatible material, such as titanium, steel, oraluminum.

As shown in FIG. 2, the driver 18 includes a driver body 34 that iselongate in the longitudinal direction L, and defines respectiveproximal and distal ends separated from each other along thelongitudinal direction L. The driver 18 further includes a coupling 42that extends distally from the distal end of the driver body 34 and anengagement member 46 that extends proximally from the proximal end ofthe driver body 34. The driver 18 may be made from any biocompatiblematerial, such as titanium, steel, or aluminum.

The coupling 42 of the driver 18 is configured to mate with acomplimentary coupling of the fixation element 14. Once the coupling 42of the driver 18 has mated with the fixation element 14, the driver 18is configured to receive a torsional force or torque, and impart thetorsional force or torque to the fixation element 14. In the illustratedembodiment, the coupling 42 is substantially star-shaped, though itshould be understood that the coupling 42 may define any suitablealternative shape as desired, such as a cruciform, a hex, or the like.

The engagement member 46 is configured to be received by or otherwiseattach to a complementary engagement member of a handle. Therefore, whenthe driver assembly 10 is to be used, an individual may attach thehandle to the driver 18 by attaching the engagement member of the handleto the engagement member 46 of the driver 18. As shown, the engagementmember 46 may define a hexagon, though it should be understood that theengagement member 46 may define other shapes that allow the driver 18 tobe coupled to a handle.

As shown in FIG. 2, the driver 18 further includes a first protrusion 50that extends radially outward from the driver body 34 proximate to theproximal end of the driver body 34, and a second protrusion 54 thatextends radially outward from the driver body 34 at a location that isdistal to the first protrusion 50. As shown, the first protrusion 50 andthe second protrusion 54 are spaced apart along the driver body 34 by adistance d. The first and second protrusions 50 and 54 can be annular oralternatively shaped, such that the first protrusion 50 is generallysmooth and defines a first diameter or alternative cross-sectionaldimension D₁, and the second protrusion 54 includes threads 58 anddefines a second diameter or alternative cross-sectional dimension D₂that is less than the first cross-section dimension D₁. The first andsecond protrusions 50 and 54 are configured to limit the translation ofthe driver 18 within the holding sleeve 22 in the longitudinal directionL.

As shown in FIGS. 1B-1D, and 3A, the holding sleeve 22 is elongate inthe longitudinal direction L and is configured to receive the driver 18such that either or both of the driver 18 or the holding sleeve 22 cantranslate in the longitudinal L direction relative to the other. Asshown in FIG. 1D, the holding sleeve 22 includes a holding sleeve body60 and a channel 64 that extends through the holding sleeve body 60 inthe longitudinal direction L. The distal end of the holding sleeve body60 defines a fixation element coupler 66 that is configured totemporarily hold a fixation element. In the illustrated embodiment, thefixation element coupler 66 includes internal threads 68 defined withinthe distal end of the channel 64. The internal threads 68 are configuredto engage external threads of the fixation element 14 to therebysecurely hold the fixation element 14 to the holding sleeve 22. Thoughit should be understood that the fixation element coupler 66 may includeexternal threads 69 that are configured to engage internal threads ofthe fixation element 14, as shown in FIG. 3B. Similarly, the proximalend of the channel 64 defines a coupling feature such as internalthreads 72 that are configured to be engaged by the threads 58 of thesecond protrusion 54 of the driver 18 so as to couple the holding sleeve22 to the driver 18. The channel 64 defines a recessed portion 80 distalto the threads 72, that has a diameter capable of allowing the driver18, and more particularly the second protrusion 54 of the driver 18 totranslate and rotate freely within the holding sleeve 22 for apredetermined distance.

To couple the driver 18 to the holding sleeve 22 to thereby form adriver-holding sleeve assembly, the driver 18 is inserted into thechannel 64 of the holding sleeve 22 through a proximal opening of thechannel 64. The driver 18 is advanced through the channel 64 by simpletranslation of the driver 18 until the internal threads 72 of thechannel 64 abut the threads 58 of the driver 18. The driver 18 may thenbe rotated until the second protrusion 54 of the driver 18 is threadedpast the threads 72 of the channel 64 and the second protrusion 54 isdisposed within the recessed portion 80 of the channel 64. As shown inFIG. 1D, while the second protrusion 54 of the driver 18 is disposedwithin the recessed portion 80, the driver 18 may be translated distallyuntil the first protrusion 50 abuts a proximal end of the holding sleeve22. Thus, the first protrusion 50 defines a stop configured to abut theproximal end of the holding sleeve 22 when the driver is fully insertedinto the holding sleeve 22.

Referring now to FIGS. 1C, 1D and 3A, the holding sleeve body 60 definesa distal portion 82 and a proximal portion 84. The distal portion 82 hasa diameter or cross-sectional dimension that is less than the diameteror cross-sectional dimension of the proximal portion 84 such that ashoulder 86 is defined at the juncture of the distal and proximalportions 82, 84. The holding sleeve body 60 defines a groove or slot 88extending through the proximal portion 84 that is configured to beengaged by a spring finger defined by the alignment mechanism 26. Theinteraction between the spring finger of the alignment mechanism 26 andthe groove 88 limits the longitudinal translation of the alignmentmechanism 26 as will be described.

As shown in FIGS. 1B-1D, and 4, the alignment mechanism 26 includes analignment body 90, and defines a channel 94 that extends through thealignment body 90 in the longitudinal direction L. The alignment body 90includes a first section 98 and a second section 102 that is disposedproximal with respect to the first section 98, such that the first andsecond sections 98 and 102 join at a juncture 104. The second section102, has a diameter or other cross-sectional dimension that is greaterthan the diameter or other cross-sectional dimension of the firstsection 98. In particular, the channel 94 of the second section 102, hasa diameter or other cross-sectional dimension that is greater than thechannel 94 of the first section 98. The channel 94 of the alignmentmechanism 26 is configured to receive the holding sleeve 22 such thatthe alignment mechanism 26 may translate distally or proximally apredetermined distance.

As shown in FIG. 4, the alignment mechanism 26 further includes a pairof struts 106 that each have a strut body 109 that extends laterally outfrom the holding sleeve 22. In particular, each strut body 109 extendslaterally out from the distal portion 98 of the alignment mechanism body90. As shown, the struts 106, also extend distally past the distal endof the alignment body 90. The struts 106 are separated along a lateraldirection that is substantially perpendicular with respect to thelongitudinal direction, such that a gap 110 is defined between the twostruts 106 adjacent a distal opening of the channel 94. As shown, eachstrut 106 includes an alignment member 114 that extends distally fromthe strut body 109. In the illustrated embodiment, the alignment members114 are pegs or cylindrical rods, however, it should be understood thatthe alignment members 114 may define any shape as desired. The alignmentmembers 114 are configured to engage the underlying structure to whichthe fixation element 14 is to be affixed so as to align the driverassembly 10 as well as the fixation element 14 to the underlyingstructure when the fixation element 14 is to be affixed to theunderlying structure.

As shown in FIG. 4, the alignment mechanism 26 can further include arail 118 that extends out from at least one of the strut bodies 109 andinto the gap 110. As shown, the two rails 118 extend parallel to eachother in the longitudinal direction L, and are disposed opposite to eachother within the gap 110. The rails 118, and thus the alignmentmechanism 26, are configured to engage the blocking plate 16 as thefixation element 14 is temporarily coupled to the holding sleeve 22. Asthe fixation element 14 is advanced into an intervertebral implant, therails 118 are configured to guide the blocking plate 16 through the gap110. The rails 118 maintain the alignment of the blocking plate 16 withthe intervertebral implant as it is being affixed to the intervertebralimplant.

The second section 102 of the alignment body 90 includes a flexiblefinger 130 that is configured to engage the groove 88 of the holdingsleeve 22. As shown in FIG. 1D, the proximal end of the finger 130defines a protrusion 134 that extends into the groove 88 when the finger130 is engaged with the groove 88 to thereby hold the alignmentmechanism 26 to the holding sleeve 22. As shown in FIG. 1D, the juncture104 between the first section 98 and the second section 102 of thealignment body 90 forms a shoulder 138 within the channel 94 of thealignment mechanism 26. The protrusion 134 of the finger 130 and theshoulder 138 form a recess 142 therebetween and within the channel 94that allows the alignment mechanism 26 to translate distally andproximally relative to the holding sleeve 22 without interference fromthe holding sleeve 22. The longitudinal length of the groove 88determines the distance that the alignment mechanism 26 can travel. Thatis, the alignment mechanism 26 may travel distally along the holdingsleeve 22 until the protrusion 134 of the alignment mechanism's finger130 abuts the distal end of the groove 88 of the holding sleeve 22.

The alignment mechanism 26 may be coupled to the holding sleeve 22 bysliding the alignment mechanism 26 over the distal portion 68 of theholding sleeve 22. As the alignment mechanism 26 is being slid along theholding sleeve 22 the flexible finger 130 of the alignment mechanism 26flexes up and rides longitudinally along an external surface of theholding sleeve 22. Once the finger 130 reaches the groove 88 defined bythe proximal portion 72 of the holding sleeve 22, the finger 130 canflex back to its original position and into the groove 88 to therebycouple the alignment mechanism 26 to the holding sleeve 22. As shown inFIG. 1C, the assembly 10 may also include a spring 158 that is disposedabout the distal portion 68 of the holding sleeve 22 and within therecess 142 defined by the second section 102 of the alignment mechanism26. The spring 158 is there to resist linear motion of the alignmentmechanism 26.

The driver assembly 10 may be configured to drive a fixation element 14into an underlying structure. In one embodiment and in reference toFIGS. 5A-5D, the fixation element 14 may define a screw that includes ashaft 160 that defines longitudinally opposing proximal and distal ends160 a and 160 b, respectively, and a head 164 coupled to the proximalend 160 a of the shaft 160 either directly or indirectly via anunthreaded neck that is coupled between the proximal end 160 a of theshaft 160 and the head 164. Helical threads 168 extend radially out fromthe shaft 160 at locations at and between the proximal and distal ends160 a and 160 b that are configured to engage complementary threads onthe inner surface of a central bore of the fixation plate of theintervertebral implant. Thus, a substantial entirety of the shaft 140between the proximal and distal ends 160 a, 160 b may be threaded. Asshown, however, a proximal end of the shaft 160 may be void of thethreads 168.

Similarly, the fixation element 14 includes helical threads 176 thatextend radially out from the head 164 at locations at and betweenproximal and distal ends of the head 164. The threads 176 are configuredto engage the threads 68 of the holding sleeve 22 to thereby temporarilycouple the fixation element 14 to the holding sleeve 22. As shown inFIG. 5D, the pitch of the threads 168 of the shaft 160 can besubstantially equal to the pitch of the threads 176 of the head 164.Furthermore, the threads 168 and the threads 176 may have the same pitchdirection or pitch rotation direction or handedness (i.e. right handedthreads or left handed threads). That is the threads 168 and the threads176 may extend helically around the shaft 160 and the head 164respectively at substantially the same angle and in the same direction.Therefore, when the fixation element 14 is driven into an underlyingstructure, the fixation element 14 disengages from the holding sleeve 22at the same rate that it engages the underlying structure. Though itshould be understood that the pitch could be made to be differentbetween the threads 168 of the shaft 160 and the threads 176 of the head164 to achieve different ratios of linear motion into the underlyingstructure as compared to the disengagement from the holding sleeve 22.For instance the fixation element 14 can disengage from the holdingsleeve 22 at a rate that is faster or slower than the rate at which thefixation element 14 engages the underlying structure. Furthermore, thefixation element 14 may have a conical threads 176 on the head 164, withthe internal threads 68 of the holding sleeve 22 matching the greatestthreaded diameter of the threads 176.

As shown in FIG. 5B, a top surface of the head 164 of the fixationelement 14 defines a coupling 180 that is configured to mate with thecoupling 42 of the driver 18. As shown, the coupling 180 can be shapedas a recessed star, or can alternatively be in the shape of a recessedcruciform, a recessed hex, or any alternative shape as desired.

The fixation element 14 may be configured to affix a variety of devicesto an underlying structure. For example, the fixation element 14 may beconfigured to affix the blocking plate 16 shown in FIGS. 6A-6E tounderlying structure configured as an intervertebral implant 204 asshown in FIG. 7. The intervertebral implant 204 can be constructed asdisclosed in U.S. patent application Ser. No. 12/761,101 filed Apr. 15,2010, the contents of which are incorporated herein by reference intheir entirety, or can be alternatively constructed as desired.Referring to FIG. 7, the intervertebral implant 204 includes a fixationplate 208 that is coupled to a spacer 212. As shown, one or morefixation members 216 may be utilized to securely anchor theintervertebral implant 204 within an intervertebral space betweenadjacent vertebral bodies. Unless otherwise indicated, theintervertebral implant 204 and its components can be manufactured fromany suitable biocompatible material known in the art including but notlimited to titanium, titanium alloy such as (TAN), stainless steel,reinforced plastics, allograft bone, and the like.

The fixation plate 208 is defined by a generally C-shaped body 220 thatdefines an anterior end 220 a and laterally opposed arms 220 d extendingposteriorly from opposite sides of the anterior end 220 a in a generallyperpendicular direction from the anterior end 220 a. The body 220further defines opposed upper and lower sides 220 b, 220 c. Theanterior, upper, lower, and arms 220 a, 220 b, 220 c, and 220 d definethe general shape of a cradle that includes an internal channel that isconfigured to receive the spacer 212, such that the arms can at leastpartially surround and engage and support the spacer 212.

The fixation plate 208 may define a pair of apertures 228 that extendinto the anterior end 220 a, and are configured to receive the alignmentmembers 114 of the driver assembly 10. The apertures 228 may beD-shaped, circular or any other desired shape capable of receiving thealignment members 114 so as to operatively align the fixation plate withthe driver assembly 10, such that the driver assembly 10 is configuredto drive the fixation elements 14 into a desired target location. Forinstance, the target location can be in the form of a bore 232 thatextends into the anterior end 220 a of the fixation plate 208, and canfurther extend through the body 220. The bore 232 can be centrallydisposed between the arms 220 d. The bore 232 is defined by an innersurface 232 a of the body 220 that defines threads 236 that areconfigured to engage the complimentary threads 168 formed on the shaft160 of the fixation element 14. The fixation plate 208 may also define arecess 240 that extends into the anterior end 220 a and is configured toreceive a complementary surface of the blocking plate 16.

As shown in FIG. 7, the fixation members 216 extend through the fixationplate 208 within the recess 240 and about the bore 232. The fixationmembers 216 can, for instance, extend through the fixation plate 208 ata trajectory that allows the members 216 to engage the vertebral bodiesthat define the intervertebral space in which the intervertebral implant204 is disposed. The blocking plate 16 when affixed to the fixationplate 208, covers the proximal ends of the fixation members 216, therebypreventing the fixation members 216 from backing out or otherwisedisengaging from the vertebral bodies.

Now referring to FIGS. 6A-6E, the blocking plate 16 includes a generallydisc shaped body 260 with an anterior surface 260 a and a posteriorsurface 260 b. The anterior surface 260 a of the body 260 may begenerally planar, or may be defined to match the anterior end 220 a ofthe fixation plate 208 when the blocking plate 16 is fully affixed tothe fixation plate 208. Similarly the posterior surface 260 b of theblocking plate 16 may be substantially planar, or may be defined tomatch the recess 240 formed in the anterior end 220 a of the fixationplate 208 when the blocking plate 16 is fully affixed to the fixationplate 208. By having the posterior surface 260 b match the recess 240 ofthe fixation plate 208 the blocking plate 16 will abut or otherwise lieflush against the recess 240. The posterior surface 260 b can define across-section less than that of the anterior surface, though it shouldbe appreciated that the blocking pate 16 can be alternatively shaped asdesired.

As shown in FIGS. 6A-6C the blocking plate 16 further defines anaperture 280 that extends through the body 260 along a direction betweenthe anterior surface 260 a and the posterior surface 260 b. The aperture280 can by cylindrical or any suitable alternative shape, and can thusdefine a diameter or cross-section that is substantially equal to thatof the bore 232 of the fixation plate 208. The inner surface thatdefines the aperture 280 may have threads 284 formed thereon, thethreads 284 configured to engage complimentary threads 168 formed on theshaft 160 of the fixation element 14. The aperture 280 may further bedefined by a concavity 288 that is recessed in the anterior surface 220a. The concavity 288 can be configured to receive the head 164 of thefixation element 14.

As shown in FIGS. 6B, 6C, and 6E, the blocking plate 16 further definesa pair of grooves 292 that extend through the body 260 on either side ofthe aperture 280. The grooves 292 generally define C-Shaped channelsthat are configured to receive the rails 118 defined by the alignmentmechanism 26 of the driver assembly 10. In operation as the fixationelement 14 is drawn into the holding sleeve 22, the rails 118 of thealignment mechanism 26 slide into or otherwise engage the grooves 292 ofthe blocking plate 16 to prevent the blocking plate from rotating, andto maintain its alignment with the fixation plate 208 of theintervertebral implant 204. In other words, the rails 118 are sized andshaped substantially equal to the grooves 292 such that interferencebetween the rails 118 and the blocking plate 16 prevents the blockingplate from rotating or otherwise changing its orientation once the railsare disposed in the grooves.

In reference to FIGS. 8A-8G, the driver assembly 10 may temporarilyhold, align, and subsequently affix the fixation element 14 and theblocking plate 16 to an underlying structure such as the fixation plate208 of the intervertebral implant 204. As shown in FIG. 8A, the blockingplate 16 may be threaded onto the shaft 160 of the fixation element 14before the fixation element 14 is attached to the driver 18 of thedriver assembly 10. In particular, after the blocking plate 16 isattached to the fixation element 14, the coupling 42 of the driver 18may engage the coupling 180 of the fixation element 14. By rotating thedriver 18 relative to the holding sleeve 22, the fixation element 14 maybe drawn into the fixation element coupler 66 of the holding sleeve 22such that the threads 176 defined on the head 164 of the fixationelement 14 engage the threads 68 defined in the channel 64 of theholding sleeve 22, as shown in FIG. 8B. This prevents the fixationelement 14 and the attached blocking plate 16 from falling or beingpushed off of the driver assembly 10 during the procedure. The fixationelement 14 may be coupled to the holding sleeve 22 while the alignmentmechanism 26 is drawn back or while it is past the distal end of theholding sleeve 22.

Once the fixation element 14 is retained by the holding sleeve 22, thealignment mechanism 26 may be translated forward as shown in FIG. 8C.The spring 158 on the interface between the alignment mechanism 26 andthe holding sleeve 22 can push the alignment mechanism 26 distally suchthat the rails 118 of the alignment mechanism 26 slide into the grooves292 of the blocking plate 16, thereby aligning the blocking plate 16 ina desired orientation for attachment to the fixation plate 208.

As shown in FIGS. 8D and 8E, the driver assembly 10 may then be alignedwith the fixation plate 208 such that the alignment members 114 of thealignment mechanism 26 are engaged with the apertures 228 that extendthrough the fixation plate 208, thereby ensuring that the fixationelement 14 and the blocking plate 16 are likewise aligned with thecentral bore 232 of the fixation plate 208.

As shown in FIG. 8F, once the assembly 8 is properly aligned to thefixation plate 208 the driver 18 is rotated. As the driver 18 isrotated, the threads 168 defined on the shaft 160 of the fixationelement 14 engage the threads 236 defined by the bore 232 of thefixation plate 208. At the same time, the threads 176 defined by thehead 164 of the fixation element 14 disengage from the threads 68defined by the channel 64 of the holding sleeve 22. In the illustratedembodiment, the fixation element 14 engages the fixation plate 208 atthe same rate as it disengages from the holding sleeve 22. As shown inFIG. 8F, the threads 176 defined by the head 164 of the fixation element14 become fully disengaged from the threads 68 defined by the channel 64of the holding sleeve 22 before the fixation element 14 becomes fullyseated within the fixation plate 208. When the fixation element 14 andthe blocking plate 16 have been fully seated, the driver assembly 10 maybe removed from the patient with no further disengagement step, as shownin FIG. 8G.

In another embodiment and in reference to FIGS. 9A-9E, the fixationassembly may include a driver assembly 310 that has a driver 318 and aholding sleeve 322 that is disposed about the driver 318. The driverassembly 310 can further include an alignment mechanism 326 that isintegrally formed with the holding sleeve 322. That is, the holdingsleeve 322 and the alignment mechanism 326 may be formed as a singleunit. The alignment mechanism 326 is configured to engage the underlyingstructure to which the fixation element 14 is to be affixed, so as toalign the fixation element 14 as it is being driven by the driver 318.

As shown in FIG. 9B, the driver 318 is similar to the driver 18 shown inFIG. 2. Therefore, the driver 318 is configured to couple to the holdingsleeve 322 and is configured to drive the fixation element 14 so as tocause the fixation element 14 to disengage from the holding sleeve 322while simultaneously engaging the underlying structure to which it is tobe affixed. As shown, the driver 318 includes a driver body 334, acoupling 342 that extends distally from the distal end of the driverbody 334, and an engagement member 346 that extends proximally from theproximal end of the driver body 334. The coupling 342 of the driver 318is configured to mate with a complimentary coupling of the fixationelement 14. Once the coupling 42 of the driver 18 has mated with thefixation element 14, the driver 18 is configured to receive a torsionalforce or torque, and impart the torsional force or torque to thefixation element 14. The engagement member 346 is configured to bereceived by or otherwise attach to a complementary engagement member ofa handle. Therefore, when the driver assembly 310 is to be used, anindividual may attach the handle to the driver 318 by attaching theengagement member of the handle to the engagement member 346 of thedriver 318.

As shown in FIGS. 9C and 9D, the holding sleeve 322 is elongate in thelongitudinal direction L and is configured to receive the driver 318such that either or both of the driver 318 or the holding sleeve 322 cantranslate in the longitudinal L direction relative to the other. Asshown in FIG. 9C, the holding sleeve 322 includes a holding sleeve body360 and a channel 364 that extends through the holding sleeve body 360in the longitudinal direction L. The distal end of the holding sleevebody 360 defines a fixation element coupler 366 that is configured totemporarily hold a fixation element. In the illustrated embodiment, thefixation element coupler 366 includes internal threads 368 definedwithin the distal end of the channel 364. The internal threads 368 areconfigured to engage threads of the fixation element 14 to therebysecurely hold the fixation element 14 to the holding sleeve 322. Similarto the embodiment shown in FIGS. 2 and 3A, the proximal end of thechannel 364 defines a coupling feature such as internal threads 372 thatare configured to be engaged by threads defined by the driver 318 so asto couple the holding sleeve 322 to the driver 318. Therefore, thedriver 318 and the holding sleeve 322 are coupled together in a mannerthat is similar to the coupling of the driver 18 and the holding sleeve22 shown in FIGS. 2 and 3A.

As shown in FIGS. 9C and 9D, the alignment mechanism 326 extends fromand is integral with a distal portion of the holding sleeve 322. Asshown, the alignment mechanism 326 includes a pair of struts 406 thateach have a strut body 409 that extends laterally out from the holdingsleeve body 360. As shown, the struts 406, also extend distally past thedistal end of the holding sleeve body 360. The struts 406 are separatedalong a lateral direction that is substantially perpendicular withrespect to the longitudinal direction, such that a gap 410 is definedbetween the two struts 406 adjacent a distal opening of the channel 364.As shown, each strut 106 includes an alignment member 414 that extendsdistally from the strut body 409. In the illustrated embodiment, thealignment members 414 are pegs or cylindrical rods, however, it shouldbe understood that the alignment members 414 may define any shape asdesired. The alignment members 414 are configured to engage theunderlying structure to which the fixation element 14 is to be affixedso as to align the driver assembly 310 as well as the fixation element14 to the underlying structure when the fixation element 14 is to beaffixed to the underlying structure.

As shown in FIGS. 9C-9D, the alignment mechanism 326 can further includea rail 418 that extends out from at least one of the strut bodies 409and into the gap 410. As shown, the two rails 418 extend parallel toeach other in the longitudinal direction L, and are disposed opposite toeach other within the gap 410. The rails 418, and thus the alignmentmechanism 26, are configured to engage the blocking plate 16 as thefixation element 14 is temporarily coupled to the holding sleeve 322. Asthe fixation element 14 is advanced into an intervertebral implant, therails 418 are configured to guide the blocking plate 16 through the gap410. The rails 418 maintain the alignment of the blocking plate 16 withthe intervertebral implant as it is being affixed to the intervertebralimplant.

As best shown in FIG. 9D, the rails 418 taper as they extend distally.More particularly, the rails 418 taper to a distal point 420. The distalpoint 420 of each rail 418 allows the rails 418 to more easily engagethe grooves 292 of the blocking plate 16.

In operation and in reference to FIG. 9E, the driver assembly 310 may bealigned with the fixation plate 208 such that the alignment members 414of the alignment mechanism 326 are engaged with the apertures 228 thatextend through the fixation plate 208, thereby ensuring that thefixation element 14 and the blocking plate 16 are likewise aligned withthe central bore 232 of the fixation plate 208.

As shown in FIG. 9E, once the assembly 310 is properly aligned to thefixation plate 208 the driver 318 is rotated. As the driver 318 isrotated, the threads 168 defined on the shaft 160 of the fixationelement 14 engage the threads 236 defined by the bore 232 of thefixation plate 208. At the same time, the threads 176 defined by thehead 164 of the fixation element 14 disengage from the threads 368defined by the channel 364 of the holding sleeve 322. In the illustratedembodiment, the fixation element 14 engages the fixation plate 208 atthe same rate as it disengages from the holding sleeve 322. As shown inFIG. 9E, the threads 176 defined by the head 164 of the fixation element14 become fully disengaged from the threads 368 defined by the channel364 of the holding sleeve 322 before the fixation element 14 becomesfully seated within the fixation plate 208. When the fixation element 14and the blocking plate 16 have been fully seated, the driver assembly310 may be removed from the patient with no further disengagement step.

In another embodiment and in reference to FIGS. 10A and 10B, it isrecognized that the driver assembly may be configured to temporarilyattach to a fixation element using a thin threaded rod that engagesinternal threads defined in a head of the fixation element. For example,as shown in FIGS. 10A and 10B, a driver assembly 510 includes a driver518, a holding rod 522, and an alignment mechanism 526. The driver 518includes a driver body 530 and a channel 534 that extends through thedriver body 530. The driver further includes a coupling 538 that extendsdistally from a distal end of the driver body 530. The channel 534extends through both the body 530 and the coupling 538. The channel 534is configured to receive the holding rod 522. The coupling 538 isconfigured to engage the head of a fixation element that is configuredto be affixed to an underlying structure.

As shown in FIG. 10B, the driver 518 further includes a first protrusion542 that extends radially out from the body 530 and a second protrusion546 that extends radially out from the body 530 at a location proximalof the first protrusion 542. The first protrusion 542 includes externalthreads 548 that are configured to engage threads defined by thealignment mechanism 526. To connect the driver 518 to the alignmentmechanism 526, the alignment mechanism 526 is threaded over the firstprotrusion 542. Once the alignment mechanism 526 and the driver 518 areproperly coupled, the driver 518 will be limited in its forward motionby the second protrusion 546.

As shown in FIG. 10A, the holding rod 522 is configured to translatethrough the channel 534 of the driver 518 and temporarily couple to thefixation element. As shown in FIG. 10B, the holding rod 522 includes aholding rod body 550 and a fixation element coupler 554 that thatextends distally from a distal end of the rod body 550. As shown, thefixation element coupler 554 includes external threads 558 that areconfigured to engage internal threads defined within a head of thefixation element.

In operation the holding rod 522 is threaded into the head of thefixation element 14. The alignment mechanism 526 is then alignedadjacent to a fixation plate of an intervertebral implant such that thealignment mechanism 526 engages the fixation plate. The driver 518 maythen drive the fixation element into the fixation plate. Once thefixation element has been properly placed, the holding rod 522 may beunthreaded from the head of the fixation element. The driver assembly510 may then be removed from the patient.

In another embodiment and in reference to FIGS. 11A and 11B, a driverassembly 610 may include a driver 618, and an alignment mechanism 626that comprises a two-part tube 622 that is coupled to the driver 618 andan alignment attachment 628. The driver 618 includes a driver body 630,a coupling 634 that extends distally from the driver body 630. Thedriver 618 further includes an indentation 636 formed in the driver body630 proximate to the mating feature 634.

The two part tube 622 of the alignment mechanism 626 includes a firstpart 642 and a separate second part 646. The first part 642 attaches tothe indentation 636 defined by the driver body 630 allowing it to rotatefreely relative to the driver 618. The first part 642 includes a leafspring 650 and tabs 653 that are configured to align a blocking plate.Proximal to the tabs 653 and the leaf spring 650, the first part 642includes threads 658. The second part 646 is threaded onto the threads658 of the first part 642, confining the leaf spring 650 and tabs 653.The alignment attachment 628 is attached to the second part 646 and isconfigured to align the assembly 610 to the fixation plate. Thealignment attachment 628 includes a key that allows it to slide on tothe second part 646 of the tube 622 along a groove, rotate a halfcircle, and then follow a second groove back. A spring captive on theoutside of the second part 646 provides resistive force so that driver618 does not move relative to the alignment attachment 626.

It should be appreciated that a screw fixation kit can be providedhaving components from one or more embodiments described herein. Forinstance, the screw fixation kit can include a driver assembly, and atleast one fixation element. The kit can further include a blocking patethat is configured to be affixed to an intervertebral implant. The kitcan further include the intervertebral implant that the blocking plateis affixed.

Although various embodiments have been described in detail, it should beunderstood that various changes, substitutions, and alterations can bemade herein without departing from the spirit and scope of theinvention, for instance as defined by the appended claims. Moreover, thescope of the present application is not intended to be limited to theparticular embodiments of the process, machine, manufacture, compositionof matter, means, methods and steps described in the specification. Asone of ordinary skill in the art will readily appreciate from thepresent disclosure, processes, machines, manufacture, composition ofmatter, means, methods, or steps, presently existing or later to bedeveloped that perform substantially the same function or achievesubstantially the same result as the corresponding embodiments describedherein may be utilized. For example, alternative fixation elements maybe used, such as a nail or a pin, that may be held captive forimpaction. In such a case the fixation element coupler of the holdingsleeve may be a cylinder with only a shallow bore for the head of thefixation e element, more suitable for impaction rather than a hollowtube.

1-17. (canceled)
 18. A fixation assembly comprising: a fixation elementincluding: a shaft having a distal end and a proximal end, the shaftdefining external threads between the distal end and the proximal end;and a head extending from the proximal end of the shaft, the headdefining external threads that are configured to be engaged by a driverassembly, wherein the threads of the head and the threads of the shafthave substantially similar pitches.
 19. The fixation assembly of claim18, wherein the threads of the head and the threads of the shaft areboth right handed threads.
 20. The fixation assembly of claim 18,further comprising a blocking plate, the blocking plate having a body,and an aperture that extends through the body, the aperture configuredto receive the shaft of the fixation element.
 21. The fixation assemblyof claim 20, wherein the blocking plate has a pair of grooves, eachgroove extends through the body on respective sides of the aperture. 22.The fixation assembly of claim 18, further comprising a driver assemblyconfigured to securely hold, align, and drive the fixation element intoan underlying structure.
 23. The fixation assembly of claim 22, whereinthe driver assembly includes a driver having a driver body and acoupling extending from a distal end of the driver body, the couplingconfigured to engage a coupling defined by the head of the fixationelement.
 24. The fixation assembly of claim 23, wherein the driverassembly further includes a holding sleeve having a holding sleeve body,a channel extending through the holding sleeve body, and a fixationelement coupler disposed at a distal portion of the holding sleeve body,the channel configured to receive the driver, and the fixation elementcoupler configured to temporarily hold the fixation element.
 25. Thefixation assembly of claim 24, wherein the driver assembly furtherincludes an alignment mechanism extending from the holding sleeve, thealignment mechanism having at least one alignment member configured toengage the underlying structure to which the fixation element is to beaffixed so as to align the fixation element and driver assembly withrespect to the underlying structure. 26-32. (canceled)